Your code sample looks good, and is following the example from the
developer guide[1]. There is a very simple test application in the
tests bundle that you can use as an example:
org.eclipse.mylyn.wikitext.textile.core.Main

You should be getting a text editor that is configured for wiki editing
(you should get content-assist, wiki formatting etc.) What were you
expecting? Please file a bug if you think that something is not working
properly.